Failed to remove the shaft coupling

Caraway

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I now facing one more problem. I can't find the right size new coupling online! My coupling flange diameter is 120mm. The gearbox flange diameter is 121mm. So I think it should be 4 - 3/4 inches will fit. Not see a fit one online yet! Headache!
Not quite sure what you are saying. Do you mean the pitch circle diameter (PCD) of the coupling bolt holes? Given the holes will be 1 mm biger than the coupling bolts there shouldn't be a problem. You could always take the gearbox flange off and get the new flange drilled to match (45 degrees out, in the solid metal).
 
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TheCoach

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10 Oct 2019
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Tapered key my arse.

If the engineer asked the workshop to make a joint like that he'd get told to bugger off.
Not really interested in your "arse", or indeed being a smartarse. :rolleyes: Was just trying to give some helpful input to the OP.

If its not to your liking move on, no need to be so derogatory.

TC
 

penfold

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If you do grind, on top of the good advice above get a old sheet or similar, soak in water and cover the surrounding area where sparks will land. Not only to minimise fire risk but hot sparks will embed into the grp and then rust making an awful mess(y)

TC
A towel would be more use as the terry will hold more water, or buy a fire blanket and use that.
 

Bran

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Burgundy Ben is spot on, use decent high grade bolts, lubricate them, use flat washers under the nuts, use long spanners or preferably a breaker bar. Hold the bolt head stationary, turn the nuts, keep going round all six. May need 2 MAPP blow lamps working together.
If it was me tightening those m10 nuts to their maximum I would have stripped the threads, if you haven’t stripped them you are not applying enough force.
It’s the little things that make the difference to getting that coupling off. It looks to be in too good condition to be that stuck!
 

seastoke

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boat conwy
The shaft is parallel not taper, and the coupling is about 15cm in length. I think it won't likely pop out like a bullet. It will likely need all the way pull through 15cm under that tension.

Since I already broke the puller, so I don't dare to try to use the gearbox to pull it. That will be one more headache if the gearbox broke because of that.
View attachment 119304
Were the grub screws short , as I remember on some joints , people put one grub on top of another , have you tried your allen key in the hole to see if there is another in there . Sorry someone mentioned early.
 
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SimonD

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27 Nov 2001
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Dorset
The key is just a normal square key. Not looks like any hidden trick in there. I can see the keyseat hole from behind the coupling. Just can't remove the key anyway.
Hard to see how big the key is, but could you drill and tap it then screw in a length of studding long enough to improvise a slide hammer? You may need to heat the coupling while hammering. If it doesn't come out, there's nothing lost but some time.
 
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Caraway

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... and the will to live. Cut it off.
Owning a boat is an expensive joy. The cost of a new flange isn't going to be 'the straw ' Is it?
 

Lucas Gan

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5 Oct 2018
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Thanks for all the advice.
I am now get everything ready to cut it. I have also ordered two special order slip half couplings this morning, they should be ready at the end of the week hopefully.
 

Lucas Gan

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5 Oct 2018
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I received the new coupling a few days ago. But not yet go to cut the old coupling as I'm busy on a party preparation these days. Will keep updated. Thanks.
 

Croftie

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I received the new coupling a few days ago. But not yet go to cut the old coupling as I'm busy on a party preparation these days. Will keep updated. Thanks.
So did you go for 45mm or 1.75" shaft size
 
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